“Collaborate?” He’s a reporter, let’s not assume that because the right has a deference model of reporting vis-a-vis Fox, that that is some model to be mimicked. I don’t think it is problematic to highlight Sanders’ policy positions with regards to immigration (or guns).
An activist and a reporter are not the same thing, and we shouldn’t confuse the two when one provides some inconvenient truths. The way we lionize and totemize politicians we agree with, ignoring their failings, is a route to disappointment and is what the right has succumbed to with Trump.